Field of the invention
The present invention concerns a solenoid on-off valve used for opening or closing a flow channel. A solenoid on-off valve is adapted to alternately displace a plunger in a valve chamber by a solenoid and a return spring to open or close the flow channel passing through the valve chamber. However, for attaining a normally open state in which the valve is kept at an open position and a normally closed state in which the valve is kept at a closed position by the return spring, the valve structure has to be modified so as to adaptable to the respective cases, which has been inconvenient and not economical as well.